Perimeter wound transformer



May 25, 1965 F. c. OWEN PERIMETER WOUND TRANSFORMER 5 Sheets-Sheet 1 Filed June 14, 1962 FIG. 2

R m V m FREDERICK C. OWEN A TTORNE y 1965 F. c. OWEN PERIMETER WOUND TRANSFORMER v 5 Sheets-Sheet 2 Filed June 14, 1962 FIG. 4

INVENTOR.

w N N E R W O O T T K c m E D E R F WM May 25, 1965 F. c. OWEN 3, 7

PERIMETER WOUND TRANSFORMER Filed June 14, 1962 5 Sheets-Sheet 3 FIG. 6

9 INVENTOR.

FREDERICK C. OWEN BY w w 36 ATTORNEY May 25, 1965 F. c. OWEN PERIMETER WOUND TRANSFORMER 5 Sheets-Sheet 4 Filed June 14, 1962 INVENTOR. FREDERICK C. OWEN FIG. 7

FIG. 8

A TTORNE Y May 25, 1965 F. c. OWEN 3,135,917

I PERIMETER-WOUND TRANSFORMER Filed June 14, 1962 5 Sheets-Sheet 5 FIG. 9

INVENTOR. FREDERICK C. OWEN United States Patent 3,185,917 PERIMETER WOUND TRANSFURMER Frederick C. Owen, 204 Fenton Place, Charlotte 7, NC. Filed June 14, 1962, Ser. No. 202,445 4 Claims. (Cl. 323-45) My invention relates broadly to transformers and more particularly to a transformer having a portion of the output circuit wound about the perimeter thereof.

One of the objects of my invention is to provide a construction of transformer which makes it possible to re duce the output current to Zero or increase the same to a maximum limit without employing separate reactors and at the same time maintaining the transformer open circuit voltage within a limit considered to be safe from the standpoint of the operator.

Another object of the invention is to provide a construction of A.C. welding transformer which enables the selection of a relatively low open circuit voltage considered safe to the operator in a particular environment, and which produces the effect of considerably higher voltage when an arc has been struck.

Still another object of the invention is to provide a variety of constructions of transformers wherein a portion of the output circuit is wound about the perimeter of the transformers to be magnetically coupled to the primary and secondary windings to selectively serve as a transformer output current regulating means.

Further objects of the invention are to provide A.C. welding transformer constructions that are practicable, outstanding in performance, and economical to manufacture, which provide a wide variation of and fine adjustments of output amperages between zero and maximum output; and to produce A.C. welders which eliminate the necessity of high open circuit voltages, and at the same time produce stable arc characteristics which are necessary in the welding of thin and heavy work sections.

Other and further objects of the invention reside in the manner in which extra reactors are eliminated from the welding transformers to greatly reduce the weight, amount of iron, copper and other materials as well as the amount of construction labor to greatly reduce the cost of the machines, and also in the manner in which these machines produce constant output potential characteristics that are not presently obtainable on conventional leakage type transformers unless an extra reactor is employed as set forth more fully in the specification hereinafter following by reference to the accompanying drawings in which:

FIG. 1 is a schematic diagram showing the electrical circuit of a welding transformer constructed in accordance with the present invention and particularly showing an optional condenser winding about the perimeter of the transformer;

FIG. 2 is an electrical schematic diagram, similar to FIG. 1, but showing a modified arrangement for connectng the perimeter winding into the circuit;

FIG. 3 is an electrical schematic diagram of another modified form of welding transformer constructed in accordance with the invention and similar to the transformer of FIG. 2, but showing a different arrangement of secondary circuit;

FIG. 4 is a schematic diagram similar to FIG. 3, but showing a modified arrangement of transformer primary circuit;

FIG. 5 is a schematic diagram of a transformer similar to that shown in FIG. 3, but showing a further modified arrangement of the primary winding;

. FIG. 6 is an electrical schematic diagram of a further modified form of welding transformer constructed in accordance with the invention with the primary and secondary circuits similar to those shown in FIG. l, and partic- 3,185,917 Patented May 25, 1965 ularly showing a modified form of condenser winding circuit enabling the circuit to be automatically opened when the transformer is not under load;

FIG. '7 is a schematic diagram of another modified form of the invention showing an arrangement of transformer similar to that shown in FIG. 2, but having the primary winding only on one leg portion of the core;

FIG. 8 is a schematic diagram of a further modified form of the transformer according to the invention and particularly showing a modified arrangement of the secondary circuit; and

FIG. 9 is a schematic diagram showing the teachings of the invention applied to a shell type transformer.

Heretofore in the AC. Welding transformer art, it has been necessary to employ separate reactors on leakage type transformers such as disclosed in the present disclosure, to hold the open circuit or striking voltage to a safe maximum. It is a well known fact in the welding art that the higher the open circuit voltages, on a welding transformer of this type, the more stable the welding arc; therefore it has been common practice among manufacturers of AC. electric welding machines to employ open circuit voltages as high as 156 volts, and at times even higher. These high voltages are dangerous for an operator to handle, especially around water, damp ground or concrete floors, or when welding on ships, tanks, boilers, etc. With the teachings of the present welding transformer invention it is possible to select any desred voltage that is considered safe from the operators standpoint, such as volts, or less, and still obtain the effect of considerably higher are voltage, all of which will be apparent to one skilled in the art of transformer design, manufacture and operation.

Referring to the drawings in greater detail-throughout which like reference numerals represent similar component parts, reference numeral 1 indicates a rectangular transformer core body portion which comprises a plurality of stacked iron laminae in accordance with conventional transformer practice. The core body portion 1 is comprised of a top leg portion 2, bottom leg portion 3, and side leg portions 4 and 5 interconnecting corresponding opposite ends of the top and bottom leg portions.

In the form of the invention shown in FIG. 1, the primary transformer circuit comprises primary winding 6 wound around side leg portion 4, primary winding 7 wound around bottom leg portion 3 and primary winding 8 wound around side leg portion 5, connected in electrical series with each other and in series with the primary circuit input leads 9 and iii. A main transformer secondary winding 11 is wound about primary winding 7, on bottom leg portion 3, so as to overlie this portion of the transformer primary circuit. Auxiliary secondary winding 12 is wound around top leg portion 2 of the core body portion and is connected in electrical series with the main secondary winding 11 on the bottom leg portion by means of conductor 13. For purposes of clarity, those transformer windings having other windings overlying the same have been shown in block form and the leads have been shown extending from opposite ends of each coil. The terminal of main secondary winding 11 opposite from the series connecting conductor 13 is connected to a jack plug or blade 14 of an electrical switch by means of conductor 15. In like manner the opposite terminal of auxiliary secondary winding 12 is connectedto the welding electrode holder 16 by means of conductor 17.

A third secondary winding, indicated at 18, is wound about the perimeter of the transformer core in overlying relation on the main secondary winding 11 and auxiliary secondary winding 12 on the bottom and top leg portions, with the coils of the third secondary winding lying substantially in the same plane as the coils of the other a) secondary windings, The end terminals of the third secondary winding 18 terminate in jack plug sockets or electrical switch contacts 19 and lid for selective connection with jack plug or switch blade 14-. A pair of intermediate electrical taps 21 and 22, connected to coils of third secondary winding 18 intermediate the end terminals are provided to terminate in jack plug sockets or electrical switch contacts similar to members 19 and 2%. A jack plug or electrical switch blade 23 disposed for selective electrical contact with taps 21 or 22 is connected with the work 24 by means of electrical conductor 25 and a grounding clamp or the like as in the usual practice.

The third secondary winding 18 wound around the perimeter of the transformer has no voltage in excess of the open circuit voltages produced by the main secondary winding 11 and auxiliary secondary winding 12, and by means of the switch or plug means 14, 19, 2t) and 21, 22, 23 can be connected into the welding circuit in either additive or bucking relation. The function of this third secondary winding is to give compound voltages and currents to further stabilize the welding current and to selectively increase or decrease the welding current at will without resorting to the employment of extremely high open circuit voltages which would be dangerous to those handling the welding circuits. By way of example, assuming that the main and auxiliary secondary windings 11 and 12 are wound on .the core in the same direction as the primary windings, the third secondary winding 13 would be connected additively into the secondary circuit by connecting plug 14 with socket 19, thus, for instance, providing an output welding current which would gradually range from 100 ampere s to 200 amperes, depending upon the selective connection of plug 23 with the intermediate taps 21, 22 on a 200 ampere capacity machine. With the third secondary winding 18 connected in the secondary circuit in bucking relation with plug 14 inserted in socket 20, the welding current would range gradually from 100 ampcres down to zero amperes, giving an especially good performing flow of welding arc current, even on metal as thin as 29-gage transformer iron, using diameter electrodes and a welding current of 10 amperes.

The coils of the third secondary winding 18 are linked with the electromagnetic fields of the primary and secondary windings about which the same are wound. As soon as the welding arc is struck the field of the third secondary winding builds up according to the number of coils selectively connected into the circuit in either additive or bucking relation, and since the fields of the various coils selectively connected into the circuit in either additive welding currents are produced than have heretofore been attainable, without employing separate reactors. It is to be understood that the third secondary winding 18 may be comprised of as many turns as desired, with a plurality of intermediate taps 21-22 provided for selection of a wide range of output welding current.

In addition to the third secondary Winding 18 wound about the perimeter of the transformer, I may also provide a condenser winding 26 wound about the perimeter of the transformer in like manner and connected to a suitable bank of condensers 27. Such a winding is disclosed in my patent for Transformer, Patent No. 2,136,863, is sued November 15, 193 8, for operating a relay to charge a bank of condensers, but the condensers may be connected directly to the Winding charging them as shown in my Patent No. 2,365,722, issued December 26, 1944, for Transformer. When the secondary circuit is open there is no induced voltage in the condenser winding, but when the secondary welding circuit is put under load and the secondary field is established the condenser winding is inductively coupled with the fields of both the primary and secondary circuits and the condensers 27 are thus immediately charged by the voltage induced in winding 26 as soon as the arc is struck. The condenser winding circuit reacts on the primary and secondary circuits to thereby improve the waveform of the secondary output voltage and the welding characteristics of the machine as more fully set forth in Patent No. 2,365,722. It is to be understood that the condenser winding is not an essential part of the transformer of the present invention but may be employed on each of the transformers set forth in this specification when operating conditions call for the improved performance afforded by the addition of this winding.

Performance tests on a standard 10 to 200 ampere induction arc welding machine, according to the teachings of this invention, without a condenser charging winding, designed for 220 volts operation, but operating with 200 volts AC. supplied across the primary circuit leads 9 and 113, with 350 feet of No. 3 B & S gage cable as welding leads, provided 165 amperes across the welding arc. The machine tested handles both the reversed polarity electrodes (Fleetweld No. 5), straight polarity and bare electrodes more elfectively than competitive A.C. welding machines.

A transformer very similar to that shown in FIG. 1 is disclosed in FIG. 2, but showing a modified arrangement of the secondary circuit, and the absence of the condenser charging unit. The primary transformer circuit is disposed about the core body portion in the same manner as shown in FIG. 1, with the main secondary winding 11 disposed about primary winding 7 and auxiliary secondary winding 12 disposed about upper leg portion 2 of the core. A larger third secondary winding is shown at 18 wound around the perimeter of the transformer in a similar manner to winding 18 in FIG. 1, the winding being provided with opposite end terminals 19' and 20 and a plurality of intermediate taps indicated generally at 28 for selective connection with the work 24 through conductor 25 and jack plug 23. All three secondary windings 11, 12 and 18 may be connected in series in an additive direction, as discussed with regard to FIG. 1, or the main and auxiliary secondaries may be reversely connected to the winding 18' around the perimeter of the transformer, such as by connecting one end of the auxiliary secondary 12 to end terminal 20 of the third secondary winding by means of conductor 15 and plug 14', thus connecting Winding 18' in bucking relation to the secondary windings 11 and 12. In the arrangement shown, windings 11 and 12 are connected in series additively by means of conductor 13 and the opposite end of main secondary winding 11 is connected to electrode holder 16 by means of conductor 17'. The connection between the main secondary winding 11 and auxiliary secondary winding 12 may be reversed by reversal of the appropriate combination of conductors 13, 15' and 17' so that the main secondary winding 11 bucks the auxiliary secondary winding 12, or vice versa, and then either winding connected additively or bucking to the perimeter or third secondary winding 18 by the appropriate c0nnection of conductor 15' with end terminals 19 or 20, respectively. The selective connection of plug 23 with the desired third secondary winding taps 28 is optional with the operator so that he may selectively increase or decrease the current in the secondary circuit to suit the job at hand without increasing the value of the open circuit voltage beyond safe limits.

The transformer arrangement shown in FIG. 3 is very similar to that shown in FIG. 2 with the primary circuit connected in the same manner across the input leads 9 and 10 and with the perimeter secondary winding 18' arranged about the perimeter of the transformer, and with the intermediate taps 28 connected with the work 24 in the same manner as shown in FIG. 2. In this form of the invention, the secondary circuit is comprised of only a single winding 29 wound about the upper leg portion 2 of the core body portion 1 with the perimeter secondary winding 18 wound about primary Winding 7 on leg portion 3 and secondary winding 29 on leg portion 2, as shown. Electrode holder 16 is connected to one terminal of secondary winding 29 by means to conductor 17,

forms of the invention.

former. sired from a transformer of the type shown in FIGS. 3

while the other terminal of secondary winding 29 is selectively connectable to terminals 19' or through conductor and plug 31 to connect the perimeter winding 18' in either additive or bucking relation therewith. The transformer disclosed in FIG. 4 is very similar to that disclosed in FIG. 3, with primary winding '7' wound about bottom leg portion 3 and secondary winding 29 wound about upper leg portion 2 of the core, remote from primary winding 7 in a manner similar to the arrangement of FIG. 3. In this form of the invention the primary circuit comprises only a single primary winding 7 wound about bottom leg portion 3 with no portion of the primary circuit wound about side leg portions 4 and 5 of the core, as shown in the previous The secondary circuit connec tion between secondary winding 29, perimeter secondary winding 18', electrode holder 16 and work 24- is similar to that discussed with regard to the circuit of FIG. 3.

The secondary winding 29 shown in FIGS. 3 and 4, remotely positioned from the primary circuit, governs the open circuit voltage produced by these configurations of transformer. The perimeter secondary winding 18', whichis wound on the outside of the transformer, over primary winding 7 and secondary winding 29, governs the amperage or secondary current generated in the trans If an open circuit voltage of 90 volts is deand 4, only one current value, that is approximately 100 amperes can be obtained from secondary winding 29 while at the same time keeping the voltage constant. Therefore, the function of the perimeter wound secondary 18 is to increase the secondary current when it is connected in an additive relation to the voltage regulating secondary winding 29. The increase in secondary current is proportional to the number of turns of perimeter winding 18 which are connected into the secondary circuit by means of member 23 and taps 28. When the perimeter winding 18' is connected in bucking relation to the voltage regulating secondary winding 29 the secondary current is reduced in proportion to the number of turns bucking said secondary winding 29. Therefore, it requires considerably less copper, transformer iron, and labor to pro duce these arrangements of transformer than is required to produce a similar capacity transformer constructed according to the normal practice. The taps 28 provided for reducing or increasing the secondary current aiford fine adjustments of welding heats in a relatively simple manner.

In FIG. 5 a transformer is disclosed in which the primary circuit consists of primary winding t) wound on side leg portion 4 and primary winding 8 wound on side leg portion 5, connected in series with each other by means of con ductor 32 and connected across primary input leads 9 and 10, with no portion of the primary circuit wound about either the top or bottom leg portions 2 and 3 of the transformer core. A single secondary voltage regulating winding 29 is wound on either the top or bottom leg portion 2 or 3 of the core, between two primary windings with a perimeter secondary winding 18' wound about the perimeter of the core body portion 1 on the outside of secondary winding 29'. The secondary circuit connections between secondary winding 29', perimeter winding 18, electrode holder 16 and work 24 are the same as those discussed in connection with FIGS. 3 and 4, and the transformers operate in substantially the same manner. The distributed primary circuits shown in FIGS. 1, 2, 3 and 5 otter advantages not obtainable by other arrangements of primary windings which would be desirable in particular cases.

Another modified form of the invention has been shown in FIG. 6, which discloses a welding transformer having a single primary winding 7 wound on the bottom leg portion 3 of the rectangular core body portion with a main secondary winding 11 wound on primary winding 7 in overlying relation, and a condenser winding wound are-5,91?

on main secondary winding 11 in overlying relation, such that windings 7, 11 and 35 are concentrically arranged about bottom leg portion 3. An auxiliary secondary winding 12 is provided on the top leg portion 2 with a condenser Winding 37 wound concentrically :thereover. Primary winding '7 is connected across the input leads 9 and 1t) and main secondary winding 11 and auxiliary secondary winding 12 are connected in series additive by means of conductor 13. A perimeter or third secondary winding 18 is wound around the perimeter of the trans former on the outside of condenser windings 35 and 37 and is provided with terminals 19 and 29 similar to the corresponding winding in FIG. 1, with a plurality of intermediate current adjusting taps, a pair of which are indicated at 21 and 22. The connections of the secondary circuit between main secondary winding 11, auxiliary secondary winding 12, perimeter secondary winding 18, electrode holder 16 and work 24 are the same as shown and discussed in connection with the arrangement of FIG. 1, except that a larger perimeter winding 18 is shown in this instance. As in the form of the invention shown in FIG. 1, the main and auxiliary secondary windings open circuit voltages remain constant regardless of whether the perimeter winding 18 is connected additive or bucking into the secondary circuit.

A bank of condensers, indicated at 33, having an automatic contactor 36, such as a solenoid or the like, connected in series therewith, are connected across condenser winding 35. In like manner the serially connected arrangement of automatic contactor 38 and condenser bank 34 is connected across the terminals of condenser winding 37. It is to be noted that the condenser windings 35 and 37 are not electrically connected with each other. The energizing winding 39 of a clapper-type contactor is connected in series with coil 40 Wound around one side leg portion of the transformer core body portion. When the transformer secondary circuit is placed under load a magnetic distortion is created in the core body portion due to the transformer leakage flux, thus creating a voltage within coil 40 which energizes clapper winding 39 pulling the contact members 41 and 42 into electrical engagement. The energizing coils of automatic contactors 36 and 38 are connected in parallel across a voltage source such as winding 43 wound around a side leg portion of the transformer core and having the contact members 41 and 42 connected in series with winding 43 to automatically energize coils 36 and 38 when the transformer secondary circuit is placed under load. It is to be understood, however, that in lieu of winding 43 the voltage for energizing the automatic contactors may be obtained from either the primary or secondary winding. When the clapper-type contact is energized due to the secondary being placed under load the contact members 41 and 42 move into contact with each other thus closing the energizing circuit for the automatic contactors 36 and 3S, and these members are held in contact until the load is relieved or until the Welding arc is broken, and in which instance the spring-biased contact member 41 is released by energizing coil 39, thus opening the automatic contactor energizing circuit. Both banks of condensers 33 and 34 may be used simultaneously as per the arrangement shown or either bank of condensers may be used separately according to the type of work to be performed. The condenser circuits shown in this arrangement may be used on all of the other transformers set forth in the drawing, and the clapper-type energizing switch for the condenser bank may also be employed on any or all of the other transformer arrangements since there is a pronounced leakage flux in all of these transformers, when the secondary is under load, which may be utilized for energizing the clapper-type contactor.

In FIG. 7 I have shown an arrangement of transformer circuit very similar to that shown in FIG. 2, except that in this form of the invention the transformer primary circuit comprises only a single primary winding 7, wound about bottom leg portion 3 of the core. The remainder of the circuit is substantially the same as that shown in FIG. 2 and it is again pointed out that by suitable connection of conductors 13, and 17' with main secondary winding 11, auxiliary secondary winding 12, and perimeter winding 18, the latter may be connected additively or bucking into the secondary circuit with either or both of the main secondary and auxiliary secondary windings. For this purpose, conductor 13 may be provided with suitable connecting means, such as plugs, on either end thereof for connecting windings 11 and 12 in either additive relation (as shown) or bucking relation.

A simplified form of the transformer according to the invention is shown in FIG. 8 wherein the primary ircuit comprises a single primary winding 7 wound around bot tom leg portion 3 of the core and the main portion of the transformer secondary circuit comprises a secondary winding 44 wound concentrically about primary winding 7 with one end thereof connected to electrode holder by means of conductor 45 and the other end thereof terminating in plug or switch blade 46 for connecting perimeter winding 18 in either additive or bucking relation therewith in the same manner as previously described in connection with the other transformer arrangements shown. Thus in this form of the invention, the main primary and secondary winding are disposed only about one leg of the core body portion while the perimeter secodnary winding extends about the perimeter of the transformer as shown in the other forms of the invention. The function of this transformer is somewhat similar to the transformer arrangement shown in FIG. 4, except that the secondary current will be somewhat higher when welding directly off of winding .4 due to the closer proximity of the primary and secondary windings, but the open circuit voltage is equal to that obtained with the arrangement shown in FIG. 4.

Of the group of transformers disclosed and described herein, the transformers shown in FIGS. 3 and 4 are the most economical type of AC. welding transformers from a manufacturing standpoint, and produce the best welding characteristics of any A.C. machines presently available. With the addition of the condenser winding over the primary winding or on the bottom leg portion of the transformers shown in FIGS. 4 and 8 and on the bottom leg portion and/or the two side leg portions of the trans formers shown in FIGS. 2, 3 and 5, these machines are given the advantage of unity power factor or any desired power factor and in addition to providing the power factor correcting feature the condensers also tend to reduce the drop common in the primary circuit of welding transformers when under load. With the condenser winding only on the upper leg portion of the transformers shown in FIGS. 3 and 4, the efficiency of the A.C. arc is considerably increased when using the reversed polarity electrodes similar to Fleetweld No. 5. These transformer designs are different from the transformer of FIG. 1, as it is necessary to have an automatic means of opening the condenser circuit, such as shown in FIG. 6, when the transformers are not under load. In the transformer shown in FIG. 1, the condensers automatically discharge themselves when the transformer is not under load and immediately charge the instant the welding arc is struck The action of the condenser winding shown in FIG. 1 is very similar to the action of a condenser winding wound on the upper leg portion only of the transformer core of the transformers shown in FIGS. 2-8.

The adoption of the teachings of this invention on a shell-type transformer has been shown in FIG. 9. The transformer core body portion consists of a center leg portion 47 and side leg portions 48 and 49 joined at their respective ends by top and bottom leg portions 50 and 51. Main secondary winding 52 is wound about center leg portion 4-7 with one end thereof connected to the work 24 by conductor 53 and the opposite end thereof connected to a plug member 54 by means of conductor 55. Primary winding 56 is wound concentrically about secondary winding 52 with its terminals connected across the input leads 9 and it Condenser winding 57 in turn is wound concentrically about primary winding 56 and its terminals are connected across a bank of condensers indicated at 58 through automatic actuator switch 59 which is connected in series with the condenser winding and bank of condensers. A primary winding 60 is wound about the perimeter of the transformer in the same plane as the plane of the previously described winding, such as to encircle the core side leg portions 48 and 49. The two extreme ends of the perimeter wound secondary winding terminate in sockets or switch terminals 61 and 62 for selective engagement with member 54 so that this voltage regulating Winding may be connected to the main secondary winding in either additive or bucking relation as previously described. A plurality of intermediate taps 63 are brought out from the perimeter wound secondary winding 60 for selective engagement by plug or switch member 64 which electrically completes the secondary circuit to the electrode holder 16 and provides for regulation of the secondary output current. The energizing coil 65 of automatic actuator switch 59 is electrically connected to a portion of the perimeter wound secondary winding 60 as shown so as to receive an energizing voltage therefrom when the secondary is placed under load by striking the are. As soon as the arc is struck and a voltage is produced in the perimeter wound secondary winding 6%, coil 65 is energized, thus closing actuator switch 59 allowing the bank of condensers 58 to be charged by condenser winding 57. The function of the transformer shown in FIG. 9 is very similar to those shown in FIGS. 1-8, and it is considered ideal for special type work.

It is to be understood that the use of condenser windings and condensers in each of the transformer designs disclosed is optional, as the transformers will function superbly without this additional winding or windings. While I have described my inventon in certain of the preferred embodiments, I realize that modifications may be made, and I desire that it be understood that no limitations upon my inventon are intended other than may be imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. A core-type welding transformer comprising a generally rectangular core body portion formed from leg portions interconnected at substantially right angles, a primary circuit wound around at least one of said leg portions and adapted for connection to an energizing source, a main secondary winding wound concentrically with said primary circuit around the same leg portion, a load, a voltage regulating secondary winding connected in series with said main secondary winding and said load and wound over and around the main secondary winding and primary circuit on the one leg portion and the oppositely disposed leg portion of the core body portion, and said voltage regulating secondary winding being inductively related to said primary circuit, said main secondary winding and said core body portion when said load is connected to the secondary windings.

2. A shell-type welding transformer comprising a generally rectangular core body portion having opposite outer leg portions and an intermediate leg portion connected between the outer leg portions to divide the core body portion into sections, a primary winding and a main secondary winding concentrically wound on said intermediate leg portion, an additional secondary winding connected to said main secondary winding and wound over and about said opposite outer leg portions of the core body portion and in overlying encompassing relation to the concentrically wound primary and main secondary windings, and a load connected in series with said main and additional secondary windings whereby said additional secondary winding is inductively coupled to both of said primary and 59 main secondary windings and said opposite outer leg portions when the secondary is placed under load.

3. In combination with a welding transformer including a primary Winding and main secondary Winding, a voltage regulating secondary winding connected with the main secondary winding and Wound encompassingly about the transformer and over and upon the primary and main secondary windings, a reactance of a character to materially improve the power factor of the welding transformer, and an energizing winding connected to said reactsnce and wound encoinpassingly about the transformer and over and upon the primary and main secondary winding, whereby said voltage regulating secondary winding and said energizing Winding are inductively coupled with the primary and main secondary windings when the secondary is placed under load to thereby render the reactance effective only when the secondary windings are placed under load.

4. A core-type Welding transformer comprising a core body portion formed from oppositely disposed pairs of leg portions interconnected at substantially right angles, a primary circuit wound on one pair of oppositely disposed leg portions and adapted for connection to an energizing source, a main secondary winding wound upon one leg portion of the other pair of leg portions at right angles to said primary circuit, a load, and a voltage regulating secondary winding connected in series with said main secondary winding and said load and wound over and around the other pair of leg portions and the main secondary winding wound thereon, whereby said voltage regulating secondary winding and main secondary Winding are disposed substantially normal to said primary circuit and said voltage regulating secondary winding is inductively related to said primary circuit and said main secondary winding when said load is connected to the secondary windings.

References by the Examiner UNITED STATES PATENTS 1,530,649 3/25 Casper 336-471 X 1,724,935 8/29 Huet 336l84 X 2,365,722 12/44 Owen 323-50 LLOYD MCCOLLUM, Primary Examiner. 

3. IN COMBINATION WITH A WELDING TRANSFORMER INCLUDING A PRIMARY WINDING AND MAIN SECONDARY WINDING, A VOLTAGE REGULATING SECONDARY WINDING CONNECTED WITH THE MAIN SECONDARY WINDING AND WOUND ENCOMPASSINGLY ABOUT THE TRANSFORMER AND OVER AND UPON THE PRIMARY AND MAIN SECONDARY WINDINGS, A REACTANCE OF A CHARACTER TO MATERIALLY IMPROVE THE POWER FACTOR OF THE WELDING TRANSFORMER, AND AN ENERGIZING WINDING CONNECTED TO SAID REACTANCE AND WOUND ENCOMPASINGLY ABOUT THE TRANSFORMER AND OVER AND UPON THE PRIMARY AND MAIN SECONDARY WIND ING, WHEREBY SAID VOLTAGE REGULATING SECONDARY WINDING AND SAID ENERGIZING WINDING ARE INDUCTIVELY COUPLED WITH THE PRIMARY AND MAIN SECONDARY WINDINGS WHEN THE SECONDARY IS PLACED UNDER LOAD TO THEREBY RENDER THE REACTANCE EFFECTIVE ONLY WHEN THE SEOCONDARY WINDINGS ARE PLACED UNDER LOAD. 